If you are disputing then I think that this is a semantics and interpretation issue. The first sentence of the Cato Institute paper has this "During the presidential debate, Vice President Gore told the nation, “I will keep Social Security in a lockbox ...". I have always thought that meant it was there and he would keep it there, for various values and truthfulness [grin]! However I can see your point that he might have meant future tense. Further reading does show that there was a
GOP use of the lockbox metaphor in 1999 so Al Gore may have tried to preempt that during his campaign.